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The ''wellhead'' is the equipment at the surface that provides support for the tubulars inside the well, a pressure seal between the tubulars, and a means of controlling production from the well. Typically, the wellhead consists of a casing head for each casing string, a tubing head, and a Christmas tree. For each string of pipe in the well, casing, or tubing, some means of support and pressure sealing must be provided. This is the function of the casing and tubing heads. The ''Christmas tree'' provides the necessary valving and chokes to control the production from a well capable of flowing. For a well that is being pumped, the Christmas tree is replaced by wellhead equipment that accommodates the pumping operation.

The ''wellhead'' is the equipment at the surface that provides support for the tubulars inside the well, a pressure seal between the tubulars, and a means of controlling production from the well. Typically, the wellhead consists of a casing head for each casing string, a tubing head, and a Christmas tree. For each string of pipe in the well, casing, or tubing, some means of support and pressure sealing must be provided. This is the function of the casing and tubing heads. The ''Christmas tree'' provides the necessary valving and chokes to control the production from a well capable of flowing. For a well that is being pumped, the Christmas tree is replaced by wellhead equipment that accommodates the pumping operation.

Figure 1 shows a typical wellhead for a flowing well. Notice that a choke is provided to control the rate of production from the well in addition to the tubing wing valve, which provides for a complete shut-off of the production. The choke can be either fixed or variable in size. The choke is nothing more than a small orifice, usually from 1/8 to 3/4 in. in diameter, that restricts the flow rate.

[[:file:surface-production-equipment_fig1.png|Figure 1]] shows a typical wellhead for a flowing well. Notice that a choke is provided to control the rate of production from the well in addition to the tubing wing valve, which provides for a complete shut-off of the production. The choke can be either fixed or variable in size. The choke is nothing more than a small orifice, usually from 1/8 to 3/4 in. in diameter, that restricts the flow rate.

[[file:surface-production-equipment_fig1.png|thumb|{{figure number|1}}Typical wellhead for a flowing well with a single-wing, single-completion threaded manifold.]]

[[file:surface-production-equipment_fig1.png|thumb|{{figure number|1}}Typical wellhead for a flowing well with a single-wing, single-completion threaded manifold.]]